Group particles not showing up in Cycles
This should fix it, but I suggest watching some tutorials how to create grass in Blender. 

Usually it's done with hair particles, either by manipulating the hair 
https://www.youtube.com/watch?v=mZR_WKVYiX8

or duplicating mesh grass using the hair particles
https://www.youtube.com/watch?v=eshOzshjt90&amp;t=58s